What's it called? 1

[mjgtp]

Been looking around, can't find the engineering name for this:

You have a rod that passes through a thin steel plate via a slightly larger hole than the rod. When the plate rocks back on the rod, friction is created that holds the rod in place and keeps it from sliding linearly. Is there an engineering name for this? I'm finding google sucks for stuff like this.

Further, Is there any mechanical advantages if the hole in the plate that the rod passes through is oval vs circular? Is there a ratio of rod diameter to hole size for optimal clamping grip on the rod?

Hoping this makes sense

 

[Artisi]

how about "hold-back"


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[JohnRBaker]

Of course the optimal 'clamping' force would be if it were a threaded-rod, but I suspect that that wouldn't be practical.

As for a general name of such a contrivance, I can't think of one but I know exactly what you're talking about. I've seen it used on things like the spring/dampener of screen doors, where they're called the 'hold open clip':

As for the shape of the hole, I suspect that any difference in behavior between a round versus an oval hole would be minimal at best, to say knowing of orientation suddenly becoming a factor in the case of an oval hole if there was a significant difference in effectiveness.

Anyway, I hope this helps.

John R. Baker, P.E. (ret)
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[djhurayt]

On a screen door cylinder like John has posted it is called a "hold open clip"

 

[mjgtp]

Yea, I'm thinking more generically, not for a screen door. Closest name I've seen so far is a "tilt plate". Still searching for a name though. The application will be using 2011-T3 aluminum rod (0.3125" dia), and a 304 stainless steel plate 0.065" thick.

Any thoughts on an optimal hole size?

 

[JohnRBaker]

If the rod is Aluminum and the "tilt plate" is Stainless Steel, the shape of the hole may not be all that relevant if the edges of the hole are sharp enough to 'score' the face of the rod, as that will be the biggest contributor to how effective this arrangement would be in preventing it from sliding.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[ctopher]

We always called them "thinga-ma-jigs".

Chris, CSWP
SolidWorks '17
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[kjoiner]

Something similar is used on caulking guns as well.

Kyle

 

[JohnRBaker]

That's more of a linear 'ratchet' type mechanism.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[LittleInch]

I think you mean am angled friction plate mechanism. You can only get friction if the plate is at an angle to the rod is less than 90 degrees.

That tube gun thing is what I was thinking of as well.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

Try detent.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[hendersdc]

My mind went straight to bar clamps where these appear to all just be called quick release levers.

For clamps with incremental recesses in the bar the piece that mates with the recess would be called a pawl so I am going to propose the term "friction pawl".

 

[handleman]

The "linear ratchet" mechanism is simply two of these plates operating in opposite directions. The basic "tilted plate" type shaft/plate interaction is the same. Ditto for the "quick release" mechanism on the bar clamps. It's the exact same tilted plate mechanism, plus a spring to make it automatically engage. It should be noted that in all cases, this mechanism really only works in one direction - the direction where the force applied tends to increase the torque on the plate. In the other direction, it will just slide. If you're hoping for two-direction locking, you need two opposing ones.

The bigger the hole, the less surface pressure (and therefore holding force) you get when you apply a tilting torque to the plate. It's simple statics. If you're nominally line-on-line shaft to hole, then the surface force on the shaft from the plate is applied torque times thickness of the plate because the plate does not rotate . As the hole gets bigger, the plate tilts further before the edges of the hole contact the shaft, thus increasing the moment arm between the contact points and decreasing surface contact force for a given input torque. The thing you have to balance with is ease of sliding on the shaft when it's not supposed to be locked. You need at least enough clearance on the hole to allow sliding after you've boogered up the shaft... (see next paragraph)

Also, you're probably going to want to consider your materials carefully. Stainless is a fair bit harder than aluminum. The edge of the locking plate is going to cause some really high surface stresses and is pretty likely to mar the shaft. Ever used an old, cheapo caulk gun? Mine is not smooth at all anymore.

 

[IRstuff]

Cheapo is the operative word; apparently, the "better" guns have a built-in rack, so the notches are already in existence.

TTFN (ta ta for now)
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[handleman]

That's a powered gun... I have one that came in one of those cordless tool bundles. It's really not useful for your typical caulk job (maybe unless you're a pro). The slowest setting is way faster than I can lay a controlled bead. However, it's awesome for construction adhesive over large panels!

I also have a manual one with a detented shaft... Not quite a rack, but close. To retract that one, you have to spin the shaft so the advancing mechanism is no longer in contact with the detents.

 

[BUGGAR]

Monkey Paw

 

[Compositepro]

The most appropriate name that I can think of is "friction pawl".